This application generally relates to IR detectors, and in particular, to a multiband sub-wavelength IR detector having frequency selective slots, and a method of making the same.
Imaging systems typically use an array of detectors to generate an image of a target. Each individual detector element measures the intensity of energy (such as infrared or visible light) incident upon the detector element, and forms one pixel of the output image.
Mercury cadmium (“mercad”) telluride has been implemented as an absorbing element for IR detectors. By varying the alloy composition of the structure, the cut-off wavelength may be selectively tuned so as to provide broad band coverage in the long-wavelength infrared (LWIR) range (8-12 μm).
GaN and GaAs/AlGaAs quantum well infrared photodetector (QWIP) technologies have been considered for broad band LWIR response. However, the quantum efficiency at 10 μm for these systems is significantly low as they require extrinsic doping. Further, this type of detector is not readily combinable with a frequency-selective surface to enable multiple or dual band detection.
What is needed is an easily manufactured planar array with dual or multiband imaging response that overcomes the shortcomings of conventional imaging arrays.